Design, Development, and Testing of a Compact Tribocorrosion Apparatus for Biomedical Applications

Abstract

Orthopedic and dental implants experience the synergistic effect of wear and corrosion, i.e., tribocorrosion, which has been a major contributor to the premature failure of implants. This work focuses on the development of a compact and cost-effective tribocorrosion apparatus for the investigation of fretting and wear. The custom-built apparatus is validated with an analysis of the tribocorrosion behavior of Ti6Al-4V disks in artificial saliva (pH = 6.5, T = 37°C). Electrochemical impedance spectroscopy, potentiodynamic, free potential, and potentiostatic analyses were used for electrochemical characterization of Ti-6Al-4V disks. White light interferometry and scanning electron microscopy were used to analyze wear scars on the Ti-6Al-4V disks. Total wear loss was calculated to be 12.4 ± 1.5 lg, and the synergistic weight loss ratio (0.78 ± 0.1) showed that Ti-6Al-4V disks experience synergy of wear and corrosion, with wear being the dominant component.

Tribo-electrochemical behavior of bio-functionalized TiO2 nanotubes in artificial saliva: Understanding of degradation mechanisms

“…For tribo-electrochemical experiments, the open circuit potential (OCP) was monitored prior to rubbing action until stabilization, during the whole duration of sliding and after the mechanical action, during 1800 s. The electrochemical measurements were carried out using a potentiostat Gamry Reference 600 coupled to Gamry framework software (Gamry Instruments, Warminster, PA, USA). To reproduce the daily mastication of a person, the reciprocating sliding tests against alumina ball were performed at a normal load of 1 N (initial Hertzian contact pressure of 400 MPa) and at a sliding frequency of 1 Hz for 1800 s [67,68]. Furthermore, a linear displacement amplitude of 650 µm was selected to simulate the micro-movements at implant-bone interface induced by the transmitted loads during mastication [68,69].…”

In vitro Evaluation of Tribocorrosion Induced Failure Mechanisms at the Cell‐Metal Interface for the Hip Implant Application

“…Finally, when applying the E pass potential, the non‐seeded alloy also presented a wear dominating corrosion mechanism. However, the seeded surfaces presented the opposite behavior, the corrosion degradation mechanisms prevails into the wear mechanism, showing a ratio value between 1 and 10, which might be due to the high initial peak observed in the running‐in period, as observed by a previous study for steady state potentials in physiologic solutions.…”

“…Ti6Al4V samples (McMaster‐Carr, USA) of 15 mm diameter, 2 mm thickness, and nominal composition (in wt%) of balance Ti, 6.17% Al, and 4% V were mechanically polished up to mirror finish ( R a < 40 nm) in order to obtain a highly smooth surface, using a polishing method previously validated . The samples were then cleaned by sonication in ethanol for 10 min and in deionized water for 10 min, followed by air drying, based on a standard metallographic preparation procedure .…”

“…Based on previous work developed by the authors, preliminary tribocorrosion tests (not shown) were performed in order to choose the cathodic potential drop resultant from the rubbing actions on the surface under free potential conditions, from −0.25 V stable potential to −0.9 V. Based on these preliminary results and on the PD curves obtained, the tribocorrosion behavior of the bone‐stem interface was evaluated by performing potentiostatic tests (PS), applying three different potentials representing three different stages of the passive film: (i) −0.2 V/SCE, the corrosion potential ( E corr ) at which the oxide film of the Ti6Al4V alloy is under free conditions, representing a clinical scenario of resting conditions of the hip stem implant without any motion/loading inside the femur bone; (ii) −0.9 V/SCE, the cathodic potential ( E cat ) where only cathodic reactions are occurring at the surface, representing a clinical situation, where the relative motion that the stem may undergo inside the femur bone can lead to local destruction of the passive film; (iii) 0.7 V/SCE, the passive potential ( E pass ) at which the oxide film of the Ti6Al4V alloy is on steady‐state conditions, clinically simulating the electrochemical state of the surface at the unworn areas of the implant. Tests were carried out in a custom‐built tribometer, previously developed, described, and validated by Butt et al, using a pin‐on‐flat configuration, and the schematic diagram is presented in Figure a. The oscillation frequency of the counter‐body pin during the sliding test was controlled at 1 Hz.…”

“…The weight loss distribution in terms of total wear‐corrosion loss ( K wc ) during tribocorrosion test, estimated from the wear scar dimensions, is the sum of wear loss due to electrochemical oxidation ( K c ), using Faraday's law, and wear loss due to sliding wear ( K w ), so that: …”